Usually, a motor core formed with a laminated iron core is known which has several tens to several hundreds of annular thin sheet members laminated that are obtained by press working electromagnetic steel plates. The thickness of the thin sheet member is about 0.15 to 0.5 mm. As the thickness of the sheet member is smaller, an energy effect is supposed to be the better. Further, in order to improve a yield rate, a laminated iron core is also known which is manufactured in such a way that circular arc shaped thin sheet members obtained by dividing the annular thin sheet member into a plurality of pieces are combined together.
For instance, Patent Literature 1 discloses a device by which one annular thin sheet member is formed by a plurality of circular arc shaped segment iron core pieces and many thin sheet members formed in such a way are laminated to manufacture a laminated iron core. A central angle of the circular arc shaped segment iron core piece is 360°/p. One annular thin sheet member is formed by p pieces of segment iron core pieces. In the annular thin sheet members in layers which are respectively adjacent in a vertical direction, the circular arc shaped segment iron core pieces which respectively form the thin sheet members are laminated in such a way that their connected positions shift in the circumferential direction as if bricks were stacked.
Patent Literature 2 discloses such a manufacturing device as described below. Namely, the manufacturing device forms segment iron core pieces by a half cutting work and a plane press work when the manufacturing device manufactures an annular laminated iron core in which layers are respectively formed with a plurality of segment iron core pieces (circular arc shaped members). Then, the segment iron core pieces which are pressed back are pushed down to separate the segment iron core pieces from an iron core material (a thin sheet material). Every time that the separation is carried out, the separated segment iron core piece is arranged in a desired position of the laminated iron core and the laminated iron core is rotated by a prescribed angle to an arranged position of a next segment iron core piece. These operations are repeated to complete the laminated iron core.